Undercutting Fireplaces For Laminate Flooring

When undercutting fireplaces for laminate flooring, it can be a very dusty job. Most fireplaces are made of some sort of masonry product, such as bricks, concrete, ceramic tile or stones. When cutting this type of material it produces a lot of fine powder, which gets everywhere.

The other alternatives are to install a mold around the fireplace, which is not very attractive. Or install the laminate or hardwood up to the fireplace and fill the gap with matching putty. Fireplaces made of rock or stone will have irregular shapes that would require you to scribe around each one. This can be very time consuming, and still not look good after filling the gaps with matching putty. I always prefer to undercut the fireplace to make it look professionally done.

The idea when undercutting fireplaces for laminate flooring is to cut out the bottom of the fireplace so the laminate or hardwood flooring will slide under and look as if the fireplace was built on top of the flooring.

To undercut a fireplace you will need a specialized tool. The best tool to use is a jamb saw used for undercutting door jambs. You can use a blade that will cut the masonry with the jamb saw. There are a couple different types of these blades. The best type would be a diamond blade. This is the same type of blade used to cut ceramic tile.

I will explain how I do this using my jamb saw and a diamond masonry blade.

Setting The Blade Height When Undercutting The Fireplace

The first thing to do when undercutting fireplaces for laminate flooring is to get the height of the blade on the jamb saw set to the correct height. If the blade is set too low It is harder to cut just a little bit off after wards. If the blade is set too high, you will have a space above your flooring when installed. You want the space to be just right so when you slide the flooring under there is no space above, and it should not be hard to slide under.

Use a piece of the flooring your installing as a guide for setting the height of the saw. When setting the blade height for laminate flooring, use a piece of the uderlayment under the laminate to get the correct height. If you are gluing hardwood flooring down allow for the thickness of the glue when setting the height of your blade.

Before cutting it is a good idea to cover furniture with some plastic and cover doorways with plastic also to minimize the dust. You can use a vacuum cleaner, such as a shop vac to catch some of the dust as your making the cut. Having someone to help at this point may be needed.

There are saws that have an attachment where you can hook the vacuum tube directly to the saw. I have used this, but some dust still seems to get airborne.

In this example I am undercutting a fireplace made of brick. The bottom of which is the mortar used to hold the bricks together. This is what I need to remove.

Making The Cut When Undercutting The Fireplace

When making the cut you want to make the cut deep enough so when you slide the flooring underneath you will have an expansion gap under the fireplace. I would say at least 1/2 to 1 inch deep. After making the cut as you can see in this photo, I need to chisel the mortar out with a good chisel. A hardened steel chisel will work or an old wood chisel that you don't care about. The process of chiseling the mortar out can be tedious and time consuming. As you are doing this, use a scrap of your flooring as a guide to see how far under the fireplace you cut. I insert the scrap under and mark it with a pencil. Then you can measure it and know that the space underneath will allow you to put the flooring under and also leave an expansion gap.

There is another alternative that can make it easier to chisel out the mortar. Make a second cut, only this time set the blade flat on the floor and cut the very bottom of the mortar. The only draw back to this is you will create twice the dust. Either way you choose it is a job to do, but in the long run it looks so much better than putting a mold around the fireplace.